Random access procedure type in a wireless system

Abstract

A base station transmits, to a wireless device, one or more radio resource control (RRC) messages indicating two-step random access resources of a two-step random access type. The base station receives, while the two-step random access type and a four-step random access type are available for receiving a preamble and based on the two-step random access resources comprising contention-free two-step random access resources, a preamble via the contention-free two-step random access resources.

What is claimed is: 
     
       1. A method comprising:
 transmitting, by a base station to a wireless device, one or more radio resource control (RRC) messages indicating two-step random access resources of a two-step random access type; and 
 receiving, while the two-step random access type and a four-step random access type are available for a random access procedure and based on the two-step random access resources comprising contention-free two-step random access resources, a preamble via the contention-free two-step random access resources. 
 
     
     
       2. The method of  claim 1 , further comprising determining, while the two-step random access type and the four-step random access type are available for the random access procedure, that the two-step random access resources comprise the contention-free two-step random access resources. 
     
     
       3. The method of  claim 1 , further comprising transmitting a response to the preamble using the contention-free two-step random access resources. 
     
     
       4. The method of  claim 1 , wherein the two-step random access resources comprise:
 at least one random access channel occasion, corresponding to a downlink reference signal, for the receiving the preamble; and 
 at least one uplink grant associated with the preamble and the at least one random access channel occasion. 
 
     
     
       5. The method of  claim 4 , further comprising receiving at least one transport block from the wireless device using the at least one uplink grant. 
     
     
       6. The method of  claim 1 , wherein the two-step random access resources further comprise contention-based two-step random access resources. 
     
     
       7. The method of  claim 1 , wherein the one or more RRC messages further indicate a reconfiguration with synchronization for a handover of the wireless device. 
     
     
       8. A base station comprising:
 one or more processors; and 
 memory storing instructions that, when executed by the one or more processors, cause the base station to perform operations comprising:
 transmitting, to a wireless device, one or more radio resource control (RRC) messages indicating two-step random access resources of a two-step random access type; and 
 receiving, while the two-step random access type and a four-step random access type are available for a random access procedure and based on the two-step random access resources comprising contention-free two-step random access resources, a preamble via the contention-free two-step random access resources. 
 
 
     
     
       9. The base station of  claim 8 , wherein the operations further comprise determining, while the two-step random access type and the four-step random access type are available for the random access procedure, that the two-step random access resources comprise the contention-free two-step random access resources. 
     
     
       10. The base station of  claim 8 , wherein the operations further comprise transmitting a response to the preamble using the contention-free two-step random access resources. 
     
     
       11. The base station of  claim 8 , wherein the two-step random access resources comprise:
 at least one random access channel occasion, corresponding to a downlink reference signal, for the receiving the preamble; and 
 at least one uplink grant associated with the preamble and the at least one random access channel occasion. 
 
     
     
       12. The base station of  claim 11 , wherein the instructions further cause the base station to receive at least one transport block from the wireless device using the at least one uplink grant. 
     
     
       13. The base station of  claim 8 , wherein the two-step random access resources further comprise contention-based two-step random access resources. 
     
     
       14. The base station of  claim 8 , wherein the one or more RRC messages further indicate a reconfiguration with synchronization for a handover of the wireless device. 
     
     
       15. A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors of a base station, cause the base station to perform operations comprising:
 transmitting, to a wireless device, one or more radio resource control (RRC) messages indicating two-step random access resources of a two-step random access type; and 
 receiving, while the two-step random access type and a four-step random access type are available for a random access procedure and based on the two-step random access resources comprising contention-free two-step random access resources, a preamble via the contention-free two-step random access resources. 
 
     
     
       16. The non-transitory computer-readable medium of  claim 15 , wherein the operations further comprise determining, while the two-step random access type and the four-step random access type are available for the random access procedure, that the two-step random access resources comprise the contention-free two-step random access resources. 
     
     
       17. The non-transitory computer-readable medium of  claim 15 , wherein the operations further comprise transmitting a response to the preamble using the contention-free two-step random access resources. 
     
     
       18. The non-transitory computer-readable medium of  claim 15 , wherein the two-step random access resources comprise:
 at least one random access channel occasion, corresponding to a downlink reference signal, for the receiving the preamble; and 
 at least one uplink grant associated with the preamble and the at least one random access channel occasion. 
 
     
     
       19. The non-transitory computer-readable medium of  claim 18 , wherein the instructions further cause the base station to receive at least one transport block from the wireless device using the at least one uplink grant. 
     
     
       20. The non-transitory computer-readable medium of  claim 15 , wherein the two-step random access resources further comprise contention-based two-step random access resources.